During oil and gas drilling, a drill bit located at the end of a drill string is rotated into and through a formation to drill a well. The rate of penetration of the drill bit through the formation reflects how quickly the well is being drilled. Generally, it is unadvisable to blindly increase drilling parameters such as weight-on-bit or drill string torque in an attempt to increase the rate of penetration; doing so may cause the drilling process to catastrophically fail.
To safely and efficiently drill wells, an automatic driller may be used. Automatic drillers attempt to control the rate of penetration of the drill bit by taking into account one or more drilling parameters.